Goserelin Acetate

A to Z Drug Facts

Actions Synthetic analog of gonadotropin-releasing hormone (GnRH) that acts as potent inhibitor of pituitary gonadotropin secretion.

 Indications Alternative to orchiectomy or estrogen therapy in palliative treatment of advanced carcinoma of prostate; palliative treatment of advanced breast cancer in pre- and postmenopausal women; treatment of endometriosis.

 Contraindications Hypersensitivity to GnRH, GnRH agonist analogs, LHRH, LHRH-agonist analogs, D,L-lactic and glycolic acid polymer or acetic acid; pregnancy; breast-feeding or lactation; nondiagnosed vaginal bleeding.

 Route/Dosage Adults: SC 3.6 mg implant q 28 days into upper abdominal wall by sterile technique under health care provider supervision. SC 10.8 mg implant q 12 wk into upper abdominal wall by sterile technique under health care provider's supervision.

Interactions None well documented.

Lab Test Interferences

Diagnostic tests of pituitary-gonado-tropic and gonadal functions

Results may be misleading.

Hypercalcemia in patients with bone metastases

Drug may cause initial transient increase.

Testosterone

Drug may cause initial transient increases in serum levels.

 Adverse Reactions

CNS: Decreased libido; insomnia; headaches (in women). DERMATOLOGIC: Injection site discomfort. ENDOCRINE: Hot flashes; gynecomastia. GU: Impotence; amenorrhea; breakthrough vaginal bleeding; infertility. MUSCULOSKELETAL: Symptom flare manifested by increased bone pain during first 1 to 2 wk of therapy in patients with bone metastases.

 Precautions

Pregnancy: Category D (breast cancer); category X (endometriosis, endometrial thinning). Lactation: Discontinue the drug prior to breastfeeding. Children: Safety and efficacy not established. Special risk patients: Isolated cases of spinal cord compression and ureteral obstruction have been reported. Use with caution in patients prone to these problems. Bone mineral density changes: Decreases in vertebral trabecular bone mineral density have been observed; patients with certain risk factors (eg, alcohol or tobacco abuse, family history of osteoporosis) may be at additional risk. Hypersensitivity: Antibody formation to goserelin has been observed. Although no anaphylactic reactions have been reported, allergic reactions are theoretically possible. Prostatic cancer worsening: Drug initially causes transient increase in testosterone. Worsening of signs and symptoms of prostate cancer, such as bone pain, may occur during first few weeks of treatment. 10.8 mg implant: The 10.8 mg implant is not indicated in women as the data are insufficient to support reliable suppression of serum estradiol. Hypercalcemia: Hypercalcemia has occured in some prostate and breast cancer patients with bone metastases after starting goserelin treatment. Hormone replacement therapy (HRT): Clinical studies suggest the addition of HRT (estrogens or progestins) to goserelin may decrease the occurrence of vasomotor symptoms and vaginal dryness associated with hypoestrogenism without compromising the efficacy of goserelin in relieving pelvic symptoms. The optimal drugs, dose, and duration of treatment not established. Vaginal bleeding: Some women experience vaginal bleeding or variable duration and intensity. The bleeding represents estrogen withdrawal bleeding and is expected to stop spontaneously.

 Administration/Storage

• Clean area of upper abdominal skin with alcohol swab. Use local anesthetic to numb skin.
• Aseptically stretch skin and inject SC into upper abdominal wall. Do not aspirate.
• If blood appears in syringe, do not inject implant. Instead, withdraw needle and discard syringe. Use new syringe at different site.
• Store at room temperature.

 Assessment/Interventions

• Obtain patient history, including drug history and any known allergies.
• Assess presence of menstruation or breakthrough bleeding in women after therapy begins.
• Report increased bone pain, symptoms of spinal cord compression (eg, paresthesias, numbness, tingling, loss of sphincter control, motor weakness), ureteral obstruction (eg, pain, chills, fever, dysuria, oliguria), infection (eg, fever, chills) and increase in liver enzymes (eg, ALT, AST) to health care provider.
• Monitor closely during the first month of therapy. If spinal cord compression or renal impairment develops, institute standard treatment for these complications; in extreme cases, consider an immediate orchiectomy.
• If hypercalcemia occurs, initiate appropriate treatment.
• In the unlikely event of the need to surgically remove goserelin, it can be localized by ultrasound.
• In prostate cancer, periodically measure serum testosterone and prostatic acid phosphatase concentration to assess therapeutic response. Serum testosterone concentration should reach castrate levels after 2 to 4 wk and remain there. Prostatic acid phosphatase should approach baseline values after 4 wk of therapy.

 Patient/Family Education

• Explain to men that bone pain may intensify at beginning of therapy but will lessen over time. Discuss methods of pain management.
• Caution patient that this medication must not be taken during pregnancy or when pregnancy is possible. Advise patient to use reliable nonhormonal form of birth control while taking this drug.
• Warn women that menopausal state will be induced pharmacologically and to expect hot flushes and vaginal dryness.
• Inform patient that sexual dysfunction, decreased erections in men and infertility will occur. These side effects are probably reversible.
• Advise patient that gynecomastia may occur but will decrease when treatment is discontinued.
• Instruct patient that worsening of symptoms of prostate and breast cancer may occur during first few weeks of treatment. Advise prostate cancer patients to notify health care provider if unable to void.
• Instruct patient to report the following symptoms to the health care provider: breakthrough bleeding or menstruation, vaginitis, shortness of breath, edema, chest pain, urinary problems, pain, dizziness, depression, nausea, fever, chills.
• Advise patient that drug may cause dizziness and to use caution while driving or performing other tasks requiring mental alertness until effects of drug are known.
• Advise patient if missing ³ 1 successive doses, breakthrough menstrual bleeding or ovulation may occur with the potential for conception.
• Carefully consider the use of goserelin in patients at particular risk of developing ureteral obstruction or spinal cord compression, and monitor the patient closely during the first month of therapy. Patients with ureteral obstruction or spinal cord compression should have appropriate treatment prior to initiation of goserelin.

3.6 mg only

• Because menstruation should stop with effective doses of goserelin, the patient should notify the health care provider if regular mensutration persists. Patients missing ³ 1 successive doses may experience breakthrough menstrual bleeding, and some patients may have delayed return to menses. The patient may rarely experience persistent amenorrhea.

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Copyright © 2003 Facts and Comparisons
David S. Tatro
A to Z Drug Facts